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67 Cards in this Set
- Front
- Back
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List two genus groups of Parvoviridae family and include a disease for each.
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Erythrovirus (B19)
(Pathogenic to humans) Dependovirus (AAV - Adeno-associated virus) |
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Parvovirus unique properties:
- size - capsid - envelope - genome structure |
Smallest DNA virus
Icosahedral NO envelope Single stranded DNA |
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What does parvovirus require for replication?
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Mitotically active cells
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Parvovirus generates _______ DNA strand during the ______ phase.
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Complementary
S |
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For parvoviruses, what is required for viral transcription and replication?
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Double stranded DNA
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During parvovirus replication, the strand packaged into virions is plus or minus?
Which one has ALL genes on it? |
Can be either
Plus |
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In respect to the manifestation of symptoms, when does the contagious period occur?
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Contagious period PRECEDES symptoms.
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B19:
- transmission? - population affected? |
Respiratory droplets
Children <15 (50%) Adults by 40 (65%) Elderly (90%) |
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What causes the B19 to be resistant to inactivation?
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Lacking an envelope
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Describe the mechanism of Parvovirus spread in humans.
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1. Infects upper respiratory tract (some replication)
2. Migrate to bone marrow (replicates in erythroid precursors) 3. Viremia/Cytolysis 4. Migrate back to upper respiratory tract (replication) |
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What are the biphasic stages of B19?
Which one is infectious? Describe each. |
Initial Febrile Stage (infectious)
- virus release in respiratory secretions - viremia/cytolysis of erythroid precursors (causing erythroid production) - Erythroid production stops in 1 week Symptomatic stage (noninfectious) - Immune-mediated - Rash, arthralgia |
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List the clinical syndromes associated with the following population group:
- children - adults - immunodeficient pts - fetus - pts with increased destruction of erythrocytes |
Mild flu-like illness
Erythema infectiosum (5th dz) Mild flu-like illness Arthropathy (polyarthritis) Persistent anemia Fetal loss (hydrops fetalis) Congenital anemia Transient aplastic crisis |
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What are the population groups most at risk for B19? x5
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Pregnant women (fetal infection)
Immunocompromised pts Parents of children with B19 Elementary school aged children Sickle cell patients (aplastic crisis) |
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Erythema infectiosum:
- virus responsible - population affected - seasons involved - symptom progression |
B19
Children 4-15 Late winter to spring Unremarkable prodrome (asymptomatic/nonspecific) Followed by distint rash (slapped cheek appearance) Spreads from cheeks to extremities. |
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For adults, what are the usual symptoms associated with B19? x2
Is this preceded by something? Where are the symptoms located? |
Arthralgia and Arthritis
Usually NOT preceded by rash Hands, wrists, ankles, knees |
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In seroNEGATIVE pregnant women, what is the risk associated with B19 infection?
What is the name of the disease associated with this and what are the symptoms? When is the risk highest |
30% risk of placental infection
HYDROPS FETALIS (anemia and CHF) 2nd trimester |
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Patients with B19 infections that are also chronically hemolytic anemic (e.g.-sickle cell anemia) suffer what consequence?
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Aplastic crisis
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What do you use to diagnose B19 virus infection?
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ELISA - parvo specific IgM or IgG
PCR/Hybridization - viral DNA |
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What is the treatment for B19 infecions?
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No specific antiviral therapy.
Immune globulins Anti-inflammatory drugs Isolation of hospitalized pts |
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In normal hosts, B19 induced bone marrow replication causes what event? (something you can see in lab tests)
What causes this result? |
Decrease in hemoglobin levels
Increase in erythrocyte production |
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What viral mechanism is responsible for aplastic crisis in pts with chronic hemolytic anemia?
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Viral replication of erythroid precursors
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AAV (dependovirus) requires a second "helper" what?
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herpes virus or adenovirus
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What are the symptoms associated with infection of AAV?
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Asymptomatic
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HPV:
- genome structure |
double stranded circular DNA
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Function of HPV proteins:
- E1 - E2 |
Binds DNA at ori and promotes viral DNA replication (and has helicase activity)
Binds DNA, helps E1, and activates viral mRNA synthesis |
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For HPV, describe the actions and results of the E6 protein.
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Binds to p53, inducing its degradation.
Since p53 is the sensory protein responsible for cell arrest and apoptosis, the result is NO arrest, and NO apoptosis. |
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For HPV, describe the action and results of the E7 protein.
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E7 will interact with the pRb/E2F complex. This will cause the formation of the pRb/E7 complex and displace E2F.
E2F will then go and initiate transcription of S-phase genes allowing for DNA replication |
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What are the L1 and L2 gene products in HPV?
When are they expressed |
Structural (capsid) proteins
Expressed late |
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Papillomavirus only replicates in which part of the body?
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Epidermis of skin an dmucosa.
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Describe the life cycle of papillomavirus.
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1. The virus first infects the basal cells (stratum germinativum)
2. Expression of early genes is low (for maintenance) and causes cell hypertrophy AND decreases differentiation. 3. As the virus-infected cells reach the Stratum Spinosum, genome amplification goes up markedly. 4. This is followed by late expression of L1 and L2 capsid proteins, which only occur in the upper layers. 5. New virions are created, then released with the dying cell. |
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Why does HPV like to infect the stratum germinativum (basal cells)?
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Because these cells are mitotically active and can promote viral DNA replication.
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Why does HPV genome replication increase at the stratum spinosum?
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Because cells at this cell layer is not competent for DNA replication nor cell division.
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Decrease in differentiation leads to _________ of the epithelium.
State the effects for the following following cell layers: - S. corneum/lucideum - S. granulosum - S. spinosum |
Hypertrophy
Hyperkeratosis Parakeratosis Akanthosis |
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What is a koilocyte?
How does it form? |
Virus producing vacuolated cell.
Nucleus degenerates and large vacuole forms. |
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In HPV, the proteins _____ and _____ are oncogenes.
Their function is to initiate _______ in the ________ cells of the _________ cell layer. |
E6
E7 viral DNA replication quiescent Spinosum |
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In HPV, what is the transcription factor that regulates the expression and repression of E6 and E7?
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E2
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What is required for the progression of HPV infection to HPV carcinoma?
Describe the mechanism. |
It requires integration into the host chromosome.
This destroys the ORFs of E1 and E2. This leaves E6 and E7 unregulated, causing massive growth. |
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HPV pathogenesis is directly related to ___________ in which the virus ___________.
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Replication strategy
stimulates cell growth |
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These are HPV benign outgrowths of cells.
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Warts
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Cervical cancer is a result of this type of mechanism occurring with HPV.
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Cell transformation
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What cell layer has the highest rate of viral DNA synthesis in HPV?
What cell layer has the highest layer of late gene expression? |
Stratum Granulosum
Stratum Corneum |
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What is the most common (>90%) prognosis for HPV lesions?
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Spontaneous regression.
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Which HPV type is the most common STD in terms of seroprevalence?
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HPV 33
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List the types of HPV for the following:
- cutaneous warts - epidermodysplasia verruciformis - laryngeal papillomas - condyloma acuminatum - cervical neoplasia |
HPV 1-4
HPV 5 & 8 HPV 6 & 11 HPV 6 & 11 HPV 16 & 18 (31,33,35,39,45) |
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HPV 16 is a "high risk" HPV type that is associated with CA of what?
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Cervical, vaginal, penile, anal
Esophagus Heand and Neck |
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HPV 18 is a "high risk" HPV type that is associated with what CA?
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Adenocarcinoma
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HPV cancers affect which gender more?
What is the most common HPV induced CA? |
Women
Cervical |
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What are the risk factors for cervical cancer?
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Smoking
Persistent infection Infection with high risk HPV Compromised immune system |
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What are the tests used to diagnose HPV? x2
List positive signs. |
Microscope (hyperkeratosis)
Papanicolaou smear (koilocytosis) |
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HPV vaccine:
- contains what? - useful against what types - how effective? - what about from cervical neoplasias? |
L1 protein
HPV 16, 18 100% >70% protection |
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What are the viruses associated with human polyomavirus? x4
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BK
JC KI SV-40 |
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SV-40:
- potent virus of what - how widespread? - etiology in tumors? |
Potent DNA tumor virus
Due to contamination of poliovirus vaccine No proof indicating etiology in tumors |
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Polyomavirus:
- genome structure - envelope? - prevalence - initial replication where? - persists where? |
Circular
dsDNA Ubiquitous and persistant Respiratory tract Kidney |
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What are the functions of each strand for polyomavirus?
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One strand encodes early T (transforming) antigens.
Other strand encodes late structural genes (capsid proteins VP1 - VP3) |
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Polyomavirus is typically acquired ___________ before the age of ________.
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Asymptomatically
15 |
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Describe the spread of polyomavirus in the human body.
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1. Inoculation of respiratory tract
(multiplies there too) 2. Primary viremia 3. Goes to kidneys (multiplies there) 4. Transient secondary viremia If IMMUNOCOMPETENT: latent indefinitely in kidney If IMMUNODEFICIENT: reactivation of virus BK goes to urinary tract and multiplies JC goes to CNS |
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In immunodeficient patients, BK virus multiplication in the urinary tract can cause what diseases? x2
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Viruria
Hemorrhagic cystitis |
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In immunodeficient patients, JC virus can cause what in the CNS?
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PML
(Progressive Multifocal Leukoencephalopathy) |
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Clinically for polyomavirus:
- symptoms of primary infection - can be reactivated during what event? |
Asymptomatic
pregnancy |
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In 40% of immunocompromised patients with polyomavirus, the actual virus can be detected in what?
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Urine
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What are the BK virus related diseases associated with transplants? x2
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Ureteral stenosis in renal patients
Hemorrhagic cystitis in bone marrow transplants. |
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What is the disease associated with JC virus?
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PML
(Progressive Multifocal Leukoencephalopathy) |
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PML:
- caused by what virus? - most common population group? - physiological effect of disease - involved cells - histological revelations - symptoms x4 - mortality |
JV virus of polyomavirus
AIDS patients (~10%) Subacute demyelinating disease Oligodendrocytes Multiple foci of white matter in frontal/parietal/temporal lobes Impaired speech Impaired mentation Impaired vision Paralysis 90% death |
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What are the diseases associated with the KI virus?
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None associated YET!!!!
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T/F - KI virus can be detected in urine.
T/F - KI virus can be detected in blood. |
Both false.
Detected by PCR: (1% in nasopharyngeal aspirates) (0.5% in fecal samples) |
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How do you diagnose polyomavirus infection? x3
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PCR in:
- CSF (JCV, PML) - Urine (JCV, BKV) FISH in biopsy (JCV, PML) Urine cytological tests (enlarged cells with dense, basophilic intranuclear inclusions similar to CMV-induced inclusions) |
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Treatment for Polyomavirus infections.
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None.
Just alleviate immune suppression. |
